Difluoroamino compounds and process for the preparation thereof



United States Patent Oilfice 3,337,627 Patented Aug. 22, 1967 3,337,627 DIFLUOROAMINO COMPOUNDS AND PROCESS FOR THE PREPARATION THEREOF Kurt F. Mueller and William E. McQuistion, Washington, D.C., assignors to the United States of America as represented by the Secretary of the Navy No Drawing. Filed Mar. 22, 1965, Ser. No. 442,235 19 Claims. (Cl. 260570.5)

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to new high energy compounds and to a method of preparing difluoroamino compounds. This invention relates more particularly to the production of gem-bis(difluoroamino), 1,3,3-tris(difluoroamino) and 1,1,4,4-tetrakis(difluoroamino) compounds.

A process for making these compounds from free di fluoroamine is not desirable since it involves long reaction times and the use of a three or four step procedure. The presence of free difluoroamine also presents a safety hazard due to its explosive tendencies.

Accordingly, it is an object of this invention to produce difluoroamino compounds by a safe process that avoids the presence of free difluoroamine.

Another object is to produce the compounds by a one step reaction that has a short reaction time and good yields.

A further object is to produce the compounds by a process that can be scaled up.

Still another object is to produce particular novel high energy compounds that contain the difiuoroamino group.

The objects of this invention are accomplished by the direct reaction of difluorourea with a carbonyl compound in a nonaqueous solvent in the presence of sulfuric acid. More particularly, a difluorourea solution in a nonaro matic halo or hydrocarbon solvent is reacted in the presence of concentrated sulfuric acid with either (1) a saturated aldehyde or a saturated ketone to produce gembis(difluoroamino) compounds, (2) an mas-unsaturated ketone to produce l,3,3-tris(difiuoroamino) compounds or (3) cyclohexanedione-( 1,4) to produce the corresponding tetrakis(difiuoroamino) compound.

A wide variety of aldehydes and ketones are operable in this invention and from among these there may be mentioned (1) cycloalkanones having -8 carbon atoms. (2) cyclohexanedione (1,4), (3) compounds having the structure wherein R is hydrogen or alkyl and R is aryl, alkyl, aralkyl substituted aryl or alkyl wherein the substituents may be nitro, halo or a combination of nitro and halo groups, and (4) compounds having the structure wherein R' is hydrogen or alkyl and R" is alkyl. As examples of compounds that are represented by structures (3) and (4) there may be mentioned the alkyl phenyl ketones such as acetophenone and the like, the alkanones such as methyl ethyl ketone and the like, the haloalkanones such as S-chloropentanone and the like, the nitroalkanones such as 2,2-dinitrohexanone (5), 1,1,1-trinitropentanone (4), 1,1,1,7,7,7-hexanitroheptanone (4) and the like, the phenylaldehydes such as benzaldehyde and the like, the nitrophenylaldehydes such as nitrobenzaldehyde and the like, the alkyl aldehydes such as butyraldehyde aud the like, the halonitroalkanones such as 1- fiuoro-l,1-dinitropentanone (4) and the like and the capunsaturated alkanones such as methyl vinylketone, mesityl oxide, and the like.

As examples of the numerous nonaromatic halo or hydrocarbon solvents that may be used in this invention there may be mentioned alkanes such as pentane, hexane, heptane, octane and the like, cycloalkanes such as cyclohexane, cycloheptane and the like and chloroalkanes such as methylene, chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,2,3-trichloropropane and the like.

It is to be understood that the invention is not limited to the above compounds since they are only exemplary of the wide variety of aldehydes, ketones and solvents that are operable in this invention.

The general process of the invention comprises preparing a solution of difiuorourea in a nonaromatic halo or hydrocarbon solvent and subsequently reacting it with a carbonyl compound in the presence of sulfuric acid. The reaction mixture is stirred and when the reaction is completed the mixture is worked up by separating the organic layer, Washing it with Water and drying it over sodium sulfate. The solvent is removed by distillation and the difiuoroamino compound is purified by recrystallization if it is a solid and by distillation if it is a liquid.

The difluorourea that is used in this invention may be obtained by the process disclosed by Grakauskas in the "Abstract of Papers of 140th Meeting of the American Chemical Society, Sept. 3-8, 1961, Paper No. 51, page 23M. The ratio of difluorourea to carbonyl compound used is not critical since the reaction will proceed at any ratio but forsafety reasons the ratio should not generally exceed about 6 moles of difluorourea per one mole of carbonyl compound. The use of from about 2.2 to about 5 moles of difiuorourea per mole of carbonyl compound is preferred. The sulfuric acid added should have a concentration of about 96% or more. The concentration used is generally between about 96% and 130% with 100% being preferred for the unsubstituted aldehydes and ketones and the halogen substituted ketones and being preferred for the nitro substituted aldehydes and ketones. It is to be understood that whenever a concentration above 100% is specified, the difierence between 100% and the figure given represents sulfur trioxide. The sulfuric acid should generally be present in an amount such that there is at least about one mole of sulfuric acid per one mole of difluorourea. The upper limit of sulfuric acid present is not critical since it does not interfere with the reaction. It is generally preferred to have about 5 moles of sulfuric acid per one mole of difluorourea. The temperature of the reaction is not critical since the reaction will proceed at any temperature but for safety reasons the temperature should generally not exceed about 35 C. The preferred temperature range is about 25-30 C.

The following examples illustrate specific embodiments of the invention but it is to be understood that the scope of the invention is not limited thereto.

EXAMPLES I. 2,2-bis(difiu0r0amin0) butane A solution of 0.31 mole of difluorourea in 400 ml. of methylene chloride was placed in a one-liter, five-necked flask, fitted with two dropping funnels, thermometer, Dry Ice reflux condenser and an efficient stirrer. Methyl ethyl ketone (83 g., 0.115 mole) was added rapidly from a dropping funnel. After ten minutes 50 ml. of 100% sulfuric acid was dropped slowly into the reaction mixture at such a rate that the temperature did not exceed 29 C. A white precipitate was formed. After all the acid was added, stirring was continued for 15 hours. The Whole reaction was carried out in a nitrogen atmosphere. The

mixture was worked up by separating the organic layer, washing it with four 100-ml. portions of water and drying it over sodium sulfate. The solvent was removed by distillation through a column at atmospheric pressure. The residue yielded after a fractional distillation in vacuo 10.7 g. of 2,2-bis(difluoroamino)butane (58% yield); boiling point 3536 C./56 mm. Hg.

II. 1,1-bis( difluoroamino) butane The reaction was accomplished in the same manner as described under I above:

Difiuorourea in 410 ml. methylene chloride mole- 0.288 Butyraldehyde (9.6 g.) do 0.133 Sulfuric acid (100%) ml 50 After all of the acid was added, stirring was continued for 16 hours. The distillation yielded 5.3 g. of 1,1-bis(difiuoroamino)butane (25% yield). Boiling point was 36/ 62 mm. Hg.

III. 2,2-bis(difluoroamino) 5 -ch loropentane The reaction was accomplished in the same manner as described in I:

Difiuorourea in 150 ml. of methylene chloride mole 0.098

5chloropentanone-(2) (5.3 g.) do 0.044

Sulfuric acid (100%) ml 25 After all of the acid was added, stirring was continued for five hours. The distillation yielded 6.5 g. of 2,2-bis(difluoroamino)-5-chloropentane (71% yield); boiling point 46/2 mm. Hg.

IV. 1,I-bis(diflu0r0amino)cyclohexane The reaction was accomplished in the same manner as described in I:

Difiuorourea in 200 ml. of methylene chloride mole 0.12

Cyclohexanone (4.65 g.) do 0.048

Sulfuric acid (100%) ml 25 After adding the acid, stirring was continued for five hours. The distillation yielded 3.8 g. of 1,1-bis(difluoroamino)-cyclohexane (45% yield); boiling point 40 C./ 6 mm. Hg.

Analysis.Calcd: C, 38.6%; H, 5.4%. Found: C, 37.44%; H, 4.94%.

V. 1,1-bis(difluor0amino)-1-phenylmethane The reaction was accomplished in the same manner as described in I:

Difluorourea in 210 ml. of methylene chloride mole 0.125

Benzaldehyde (6.3 g.) in 10 ml. of methylene chloride mole 0.06 Sulfuric acid (100%) ml 25 After adding the acid, stirring was continued for four hours. The distillation yielded 5.6 g. of 1,1-bis(difluoroamino)-1-phenylmethane (49% yield); boiling point 36/ 1 mm. Hg.

AnaIysis.-Calcd: C, 43.32%; H, 3.11%; F, 39.15%. Found: C, 43.14%; H, 3.08%; F, 39.43%.

VI. 1,1-bis(diflu0roamin0)-1-phenylethane The reaction was accomplished in the same manner as described in I:

Difluorourea in 400 ml. of methylene chloride mole 0.212 Acetophenone (11.4 g.) do 0.095 Sulfuric acid (100%) ml 45 4 After adding the acid stirring was continued for six hours. The distillation yielded 11.4 g. of 1,l-bis(difluoroamino)-1-phenylethane (59% yield); boiling point 48 C./ 1 mm. Hg.

Analyris.-Calcd: C, 46.16%; H, 3.87%; F, 36.51%. Found: C, 46.60%; H, 4.20%; F, 36.07%.

VII. 2,2-dinitr0-5 ,5 -bis(difluoroamino) hexane The reaction was accomplished in the same manner as described in I:

Difluorourea in ml. of methylene chloride mole-.. 0.1

2,2-dinitrohexanone-(5) in 10 ml. of methylene chloride mole 0.032 Sulfuric acid (130%) ml 25 After adding the acid, stirring was continued for five hours. The solvent was removed under vacuum at room temperature. Seven g. of 2,2-dinitro-5,5-bis(difluoroamino)hexane were left (72% yield). Recrystallization from carbon tetrachloride or hexane; melting point 43- 45 C.

VIII. 1,1,1-trinitro-4,4-bis(difluoroamino)pentane The reaction was accomplished in the same manner as described in VII:

Difluorourea in 1000 ml. of methylene chloride mole 0.6 1,1,1-trinitropentanone-(4) do 0.215 Sulfuric acid (130%) ml After adding the acid, stirring was continued for five hours. The recrystallization from hexane yielded 48.2 g. of 1,1,1-trinitro 4,4 bis(difluoroamino)pentane (72% yield); melting point 40-4l C.

IX. 1,1-bis(difluor0amin0)-p-nitr0phenylmelhane The reaction was accomplished in the same manner as described in VII:

Difluorourea in 200 m1. of methylene chloride mole 0.094 p-Nitrobenzaldehyde (5.3 g.) in 50 ml. methylene chloride mole 0.035 Sulfuric acid (130%) ml 25 After adding the acid, stirring was continued for three hours. Yield: 7 g. of bis(difiuoroamino)-p-nitrophenylmethane (84% yield). Recrystallization from carbon tetrachloride; melting point 4749 C.

X. 1 ,1 ,4,4-tetrakis(difluoroamino) cyclohexane The reaction was accomplished in the same manner as described in VII:

Difiuorourea in 120 ml. of methylene chloride mole 0.072

Cyclohexanedione-(l,4) (1.7 g.) in 30 m1. of

methylene chloride mole 0.015 Sulfuric acid (100%) ml 25 described in I:

Mole

Difluorourea in 500 ml. of methylene chloride 0.280 Methylvinylketone (5.25 g.) 50 ml. of 100% sulfuric acid 0.075

After all the acid was added, stirring was continued for 17 hours. The distillation yielded 9.0 g. of 1,3,3-tris (difluoroamino)butane (57.5 yield); boiling point 38- 39 C./10 mm. Hg.

XII. 2,4,4-trz's(difluoroamino)-2-methylpentane The reaction was accomplished in the same manner as described in I:

Difluorourea in 200 ml. of methylene chloride mole 0.130 Mesityloxide (3.4 g.) do 0.034 100% sulfuric acid ml 25 After adding the acid, stirring was continued for five hours. The distillation yielded 3.5 g. of 2,4,4-tris(difiuoroamino) 2 methylpentane (43% yield); boiling point 39 C./mm. Hg.

Analysis.Calcd: C, 30.13%; H, 4.63%; N, 17.66%. Found: C, 30.28%; H, 5.91%; N, 17.73%.

XIII. I,1,1,7,7,7-hexanitro-4,4-bis(difluoroamino)heptane The reaction was accomplished in the same manner as described in VII:

Difiuorourea in 150 ml. of methylene chloride mole-.. 0.02 1,1,1,7,7,7-hexanitro-4-heptane 20 do 0.0058 H SO, (130%) ml 20 After adding the acid, stirring was continued for six hours. The recrystallization from n-hexane gave 0.55 g. of l,1,l,7,7,7 hexanitro 4,4 bis(difluoroamino)heptane (20% yield), melting point 808l C.

XIV. I -flur0-1 ,1 -dinitr0-4,4-bis(difluoroamino) pentane The reaction was accomplished in the same manner as described in I:

Difluorourea in 150 ml. of methylene chloride mole 0.05 1-fluoro-l,1-dinitro-4-pentanone do 0.02 130% sulfuric acid ml.. 20

After adding the acid, stirring was continued for three hours. The distillation yielded 4.7 g. of l-fluoro-l,1-di nitro 4,4 bis(difluoroamino)pentane (83% yield); boiling point 7074 C./4 mm. Hg.

Analysis.Calcd: C, 21.29%; H, 2.50%; F, 33.67%; N, 19.86%. Found: C, 21.16%; H, 2.77%; F, 34.06%; N, 18.97%.

The difluoroamino compounds produced by this invention can be used as high energy propellant ingredients (plasticizer, oxidizer, etc.) or as monopropellants. The novel compounds produced above are 1,1-bis(di fluoroamino) 1 phenylethane, 2,4,4 tris(difluoroamino) 2- methylpentane, and l-fluoro-l,l-dinitro-4,4-bis(difiuoroamino pentane.

The process of this invention has the following advantages:

(1) No free difiuoroamine is present which makes the process less hazardous.

(2) The difiuoroamino compound formed during the reaction stays in the nonaromatic halo or hydrocarbon solution which decreases the compounds sensitivity.

(3) The difluorourea is stable in the solvents and thus can be stored as a solution.

(4) The product is formed in a one step reaction.

(5) A good yield is produced in a short reaction time.

(6) The reaction can be scaled up.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A compound selected from the group consisting of 1,1 bis(difluoroamino) 1 phenylethane, 2,4,4 tris (difluoroamino) 2 methylpentane and 1 fluoro 1,1- dinitro-4,4' bis(difluoroamino) pentane.

2. The compound 1,1 bis(difluoroamino) 1 phenylethane.

3. The compound 2,4,4 tris(difluoroamino) 2- methylpentane.

4. The compound 1 fluoro 1,1 dinitro 4,4 bis(difluoroamino) pentane.

5. A process for producing difluoroamino compounds wnich comprises: reacting a solution of difluorourea in a solvent selected from the group consisting of alkanes, cycloalkanes, and chloroalkanes with a carbonyl compound selected from the group consisting of (1) cycloalkanones having from 5 to 8 carbon atoms,

(2) cycloheitanedione (1,4),

(3) compounds having the structure where R is selected from the group consisting of alkyl and hydrogen and R is selected from the group consisting of alkyl, aryl, aralkyl and substituted aryl and alkyl where the substituents are selected from the group consisting of nitro, halo, and a combination of nitro and halo groups and compounds having the structure wherein R" is selected from the group consisting of hydrogen and alkyl and R" is alkyl in the presence of concentrated sulfuric acid, said sulfuric acid being present in an amount of at least about one mole per mole of difluorourea, and recovering the corresponding difluoroamino compound.

6. A process for preparing a difiuoroamin-o compound which comprises reacting a solution of difiuorourea in a solvent selected from the group consisting of alkanes, cycloalkanes, and chloroalkanes with a carbonyl compound selected from the group consisting of (l) cycloalkanones having from 5 to 8 carbon atoms,

(2) cyclohexanedione 1,4),

(3) compounds having the structure where R is selected from the group consisting of alkyl and hydrogen and R is selected from the group consisting of alkyl, aryl, aralkyl and substituted aryl and alkyl Where the substituents are selected from the group consisting of nitro, halo, and a combination of nitro and halo groups and 4) compounds having the structure wherein R" is selected from the group consisting of hydrogen and alkyl and R' is alkyl in the presence of about 96%-130% sulfuric acid, said sulfuric acid being present in an amount of at least about 1 mole per mole of difiuorourea, maintaining the reaction temperature so that it does not exceed about 35 C., and recovering the corresponding difiuoroamino compound.

7. The process of claim 6 wherein said carbonyl compound is a chloroalkanone.

8. The process of claim 6 wherein said carbonyl compound is a nitroalkanone.

9. The process of claim 6 wherein said carbonyl compound is an alkyl aldehyde.

10. The process of claim 6 wherein said carbonyl compound is a cycloalkan-one having from 5-8 carbon atoms.

11. The process of claim 6 wherein said carbonyl compound is p-nitrobenzaldehyde.

12. The process of claim 6 wherein said carbonyl compound is acetophenone.

13. The process of claim 6 wherein said carbonyl compound is mesityloxide.

14. The process of claim 6 wherein said carbonyl compound is l-fiuoro-l,1-dinitro-4-pentanone.

15. The process of claim 6 wherein said carbonyl compound is an alkanone.

16. The process of claim 6 wherein said carbonyl compound is cyclohexanedione (1,4).

17. The process of claim 6 wherein the difiuorourea is present in an amount from about 2.3 to about 5 moles per mole of carbonyl compound.

18. The process of claim 6 wherein the temperature is maintained between about 25 and 30 C.

19. A process for producing a difluoroamino compound which comprises reacting a solution of difiuorourea in methylene chloride with a carbonyl compound selected from the group consisting of (1) cycloalkanones having from 5 to 8 carbon atoms,

(2) cyclohexanedione (1,4),

(3) compounds having the structure and R is selected from the group consisting of alkyl, aryl, aralkyl and substituted aryl and alkyl where the substituents are selected "from the group consisting of nitro, halo, and a combination of nitro and halo groups and (4) compounds having the structure References Cited UNITED STATES PATENTS 3/1967 Gould et a1. 260-483 X OTHER REFERENCES Hoffman et al., Chem. Reviews, vol. 62, page 15 (1962).

CHARLES B. PARKER, Primary Examiner.

CARL D. QUARFORTH, Examiner.

L. A. SEBASTIAN, Assistant Examiner. 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 1,1 - BIS(DIFLUOROAMINO) - 1 - PHENYLETHANE, 2,4,4, - TRIS (DIFLUOROAMINO) - 2 - METHYLPENTANE AND 1 - FLUORO - 1, 1DINITRO-4,4''BIS( DIFLUOROAMINO) PENTANE.
 6. A PROCESS FOR PREPARING A DIFLUOROAMINO COMPOUND WHICH COMPRISES REACTING A SOLUTION OF DIFLUOROUREA IN A SOLVENT SELECTED FROM THE GROUP CONSISTING OF ALKANES, CYCLOALKANES, AND CHLOROALKANES WITH A CARBONYL COMPOUND SELECTED FROM THE GROUP CNSISTING OF (1) CYCLOALKANOES HAVING FROM 5 TO 8 CARBON ATOMS, (2) CYCLOHEXANEDIONE (1,4), (3) COMPOUNDS HAVING THE STRUCTURE 